Knot theory is one area of mathematics that has an enormous number of applications. The actual functionality of many biological molecules is derived largely by the way they twist and fold after they are created. Over the years, a great deal of mathematics has been invented to describe and compare knots. The purpose of this book is to present the fundamentals of knot theory while avoiding the fine details as much as possible. Sossinsky has succeeded in doing that; he develops the machinery used to describe knots in a manner that is generally understandable. While it is necessary that the reader have some understanding of higher-level mathematics, the level does not have to be too high. It is well within the mathematical grasp of a second-year math undergraduate. There are many diagrams to aid in the understanding.